Add Django 4.0 and 4.1 PyPI classifiers

Author: adamchainz

setup.py

@@ -36,6 +36,8 @@
         "Framework :: Django :: 2.2",
         "Framework :: Django :: 3.1",
         "Framework :: Django :: 3.2",
+        "Framework :: Django :: 4.0",
+        "Framework :: Django :: 4.1",
         'Programming Language :: Python',
         'Programming Language :: Python :: 3',
         'Programming Language :: Python :: 3.7',